Bridge construction



P. A. McKENZlE.

BRIDGE CONSTRUCTION.

APPLICATION FILED MAYI3. 1920.

1,382,106, Patented June 21, 1921.

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PHILIP A. MCKENZIE, OF HOUSTON, TEXAS.

BRIDGE CONSTRUCTION.

Application filed. May 13, 1920.

To aZZ to 710m it may concern:

Be it known that I PHILIP A. MCKENZIE, a citizen of the United States,residing at Houston, in the county of Harris and State of Texas, haveinvented certain new and useful Improvements in Bridge Construction; andI do declare the following tobe a full, clear, and exact description ofthe invention, such as will enable others skilled in the art to which itappertains to make and use the same.

This invention relates to improvements in bridges and it has moreparticular reference to one which is especially designed for placementover gutters, ditches, and the like, it being such that it is adaptableas a foot bridge or as a vehicle bridge.

The object of the invention is to provide a bridge of extreme simplicityand durability which is of such construction that it may be easily andreadily placed inposition by persons unskilled in bridge construction.

Other objects and advantages of the invention will be apparent duringthe course of the following description.

In the accompanying drawings forming a part of this specification and inwhich like numerals are employed to designate like parts throughout thesame,

Figure 1 is a top plan view, partly in section, of a bridge constructedin accordance with my invention.

Fig. 2 is a longitudinal sectional view thereof, showing it in use.

Fig. 3 is a transverse section taken on the line 3-3 of Fig. 2.

Fig. at is a detail perspective view of one of the concrete slabs.

Fig. 5 is a perspective view of a slightly modified form of theinvention.

In the drawings, wherein for the purpose of illustration is shown apreferred embodiment of my invention, the numeral 1 is employed todesignate what I Shall term girders for the sake of explanation. Iemplcy a plurality of these girders, there being two used in the type ofbridge shown in Figs. 1 and 2. Each one is made from concrete, isrectangular in cross section and is provided at each end with anupstanding lug 2. I also employ a plurality of concrete slabs 3 each ofwhich is recessed at its opposite ends to provide shoulders 4:, which,when in use, rest against the inner faces of the girders 1 while thereduced end per- Specification of Letters Patent.

Patented June 21, 1921.

Serial No. 381,119.

tions 5 rest on the upper fiat faces of the girders. This constructionretains the girders in spaced relation when the bridge is erected andpreventsthem from moving inwardly. In use, the outermost slabs 3 abutthe lugs 2 and are thereby prevented against lateral displacement.

To prevent possible breakage of any of the parts of my bridge, I embedmetal reinforcing rods 6 in both the. girders and slabs. In the girdersI bend the ends of the rods 6 upwardly into the lugs 2 as indicated at7. This arrangement guards against breakage of the lugs. It is to benoted that the rods 6 are embedded in the slabs at a point be tween themiddle and the bottom so as to reinforce that part of the slab whichreceives the greatest strain and is most liable to break. It is also tobe noted that the ends of these rods are bent vertically at 8 and thenhorizontally at 9 so as to extend into and reinforce the reduced ends 5of the slabs. This construction is exceedingly strong and will withstandgreat strains.

I have shown two different types of bridges in the drawings. In Figs. 1and 2 the bridge shown is especially adapted for use as a foot bridge.On the other hand, by increasing the size of the parts of my bridge andarranging them in the manner shown in Fig. 5, Ihave a bridge which isideal for use as a driveway for vehicles. Close examination of bothforms of the invention shown will disclose the fact that theconstruction of the slabs and girders is the same in both cases, theonly difference between the two being the manner in which they arearranged. For instance in the foot bridge construction the slabs arearranged longitudinally so'as to extend crosswise of the ditch while inthe other form they are arranged to extend longitudinally of the ditch;theretore, the difference between the two forms of the bridge is a merereversal of parts which, when done, adapts the bridge for a differentpurpose.

The manner in which my bridge is erected is thought to be obvious fromthe foregoing description. It is therefore deemed unnecessary to preparea description thereof.

While I have described my bridge as being adaptable for placement overgutters and ditches, I desire it to be understood that it may be usedfor any number of different purposes.

From the foregoing de cripti n tak n in connection with the accompanyingdrawings, it is believed that persons skilled in this line of Work, willbe able to obtain a thorough understanding of the invention.

I claim: V

1. A pre-cast bridge for placement over a gutter comprising a pluralityof' concrete girders, each of which is provided at its opposite endswith an upstanding lug, and a plurality of concrete slabs associatedwith the girders, each slab having its bottom face recessed at itsopposite ends to provide shoulders which abut the vertical inner facesof the girders the reduced end portions of the slabs resting on theupper faces of the girders and the outermost slabs bearing against the.aforesaid lugs.

2. A pre-cast bridge for placement over a gutter comprising a pair ofrectangular concrete girders of uniform thickness throughout theirlengths, being provided at rality of rectangular concrete slabsassociated with the girders, "said slabs being of the same thickness asthe girders and having their underfaces notched at their opposite endsto simultaneously provide shoulders abutting the vertical inner faces ofthe girders, and reduced end portions resting on the upper faces of thegirders said reduced ends being of a thickness equal to the height ofthe lugs to render their upper faces flush with the upper ends of saidlugs,

the outermost slabs bearing against the aforesaid stops to hold theslabs together. In testimony whereof I have hereunto set my hand.

Prnmr A; MCKENZIE.

